Present credential readers suffer from a variety of limitations including high power consumption, reduced credential detection range, and a high false credential detection rate. For example, certain credential detectors of credential readers are not calibrated after a series of false credential detects which can be caused by environmental factors such as a change in temperature. In another example, certain credential detectors are calibrated by unnecessarily increasing the range of allowable impedance values, thereby desensitizing the detector, causing the effective range of the credential detector to be significantly reduced. Therefore, a need exists for further technological developments in the area of credential detectors.